The first large crater ever found under ice, the discovery could possibly be linked to a controversial extinction theory.

Today, an international team of scientists describes what they say is a huge new impact crater that lies under northwestern Greenland’s Hiawatha Glacier. If confirmed, it would be the first impact crater on Earth discovered under ice, the team reports in the journal Science Advances. At an estimated 19 miles wide, it is larger than Washington, D.C., and would rank among the top 25 known craters in the world.